Question

Suppose a gas mixture of $F,Cl,Br$ and $I$ is irradiated with photons of frequency appropriate to ionize $Cl.$ What ion(s) will be present in the mixture ?

• A. $F^{+}$ only
• B. $C{l}^{+}$ only
• C. $F^{+},C{l}^{+},B{r}^{+}$ only
• D. $C{l}^{+},B{e}^{+},I^{+}$ only

Answer 1

Answer: (D)

$C{l}^{+},B{e}^{+},I^{+}$ only

Variation in a group among the representative elements:

The ionization energy generally decreases in moving from top to bottom because the size increases due to the increase of the principal quantum number. On the other hand, the effective nuclear charge $Z_{eff}$ for the outermost electron remains almost the same along the group.

As Ionization potential of $Br$ and $I$ is less than $Cl$ so if the frequency is enough to ionize $Cl,$ then I.E. of $Br$ and $I$ would be lesser than $Cl,$ thus it can ionize them also.

So we will find all three cations in solution.